Identification of Fluorescent Small Molecule Compounds for Synaptic Labeling by Image-Based, High-Content Screening

Area of Science:

• Neuroscience
• Chemical Biology
• Molecular Imaging

Background:

• Noninvasive imaging of synapses in the living mammalian brain is limited.
• Current methods rely on genetic modification or viral delivery, posing challenges for widespread application.

Purpose of the Study:

• To develop an alternative chemical approach for synaptic imaging using small organic molecules.
• To identify novel fluorescent compounds capable of labeling synaptic structures.

Main Methods:

• An imaging-based, high-content screen was employed using cultured cortical neurons.
• A library of approximately 7000 novel fluorescent dyes was screened for colocalization with synaptic proteins.
• Follow-up studies were conducted on identified lead compounds, including CX-G3.

Main Results:

• A series of xanthone-family compounds demonstrated consistent synaptic labeling.
• The compound CX-G3 specifically labeled acidic organelles and synaptic vesicles at glutamatergic synapses.
• Labeling was observed in both cultured neurons and murine brain tissue.

Conclusions:

• The high-content screening approach is effective for identifying small molecules for synaptic imaging.
• Xanthone derivatives, such as CX-G3, show potential as synaptic markers, sensors, and targeting devices.
• This chemical strategy offers a promising alternative to genetic methods for studying synapses.